The objective of the proposed research is to elucidate the sites and mechanisms of neuroendocrine interaction as related to adrenocortical function and thus to stress response. To this end, the following experiments will be conducted: 1) Study of the effects of selective brain lesions and hypothalamic deafferentation on adrenocortical responses to sensory stimuli in order to elucidate the neural pathways which mediate these responses. (2) Investigation of the sites of action of the glucocorticoids in the negative feedback regulation of ACTH secretion, by studying the effect of hormones in animals with selective brain lesions and partial hypothalamic deafferentation. (3) Identfication, by electrophysiological methods, of the neural inputs from extra-hypothalamic limbic structures to the mediobasal hypothalamus 4) Investigation of intracellularly recorded effects of extra-cellulary iontophorised glucocorticoids on hippocampal neurons, in order to understand the mechanisms underlying the action of these hormones on neurnal excitability. 5) Detailed electrophysiological study of the synaptic oganization underlying hippocampal - septal - hypothalamic interaction.